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We investigate the electroluminescence (EL) characteristics of a hybrid light-emitting diode (HyLED) with an emissive layer comprised of CdSe/Cd/ZnS core-shell nanoparticles (NPs) embedded in poly(9,9-di-n-octylfluorenyl-2,7-diyl) (PFO) on a plastic substrate. The EL characteristics change dramatically with increasing of the biased voltage. At low voltages, recombination of electrons and holes occurs only in the PFO film because of poor charge transfer in the PFO-CdSe/Cd/ZnS NPs composite film, while the color of the light-emitting from the HyLED changes from blue to red as the biased voltage increases from 7.5 to 17.5V. We examine and discuss the mechanism of this color tunability. [ABSTRACT FROM AUTHOR]

Programmable metallization cell (PMC) memory is a kind of next generation non-volatile memory that has attracted increasing attention in recent years as a possible replacement for flash memory. In spite of the considerable amount of research focused on the fabrication of non-volatile memories on plastic substrates with lightweight, thin, and bendable characteristics, there have been few studies on the fabrication of PCM memory on flexible substrates. In this study, we synthesized AgSe nanoparticles (NPs) by a positive-microemulsion method and constructed PMC memories on plastic substrates with programmable layers formed by the spin-coating of the AgSe NPs. To the best of the knowledge, this is the first attempt to construct PMC memory on plastic substrates by the spin-coating of AgSe NPs. The AgSe NPs synthesized in this study had a uniform size of 2 nm and interestingly showed α-phase (high temperature phase) stability at room temperature. Switching behaviors were observed through the voltage scanning on the fabricated memories with applicable switching voltages. However, the resistance ratios of the off-state to the on-state were quite small. The possible reasons for the α-phase stability of the AgSe NPs at room temperature and the detailed memory characteristics will be described in this article. [ABSTRACT FROM AUTHOR]

In this study, Si-nanoparticle(NP)/Si-nanowire(NW)-based field-effect transistors (FETs) with a top-gate geometry were fabricated and characterized. In these FETs, Si NPs were embedded as localized trap sites in Al2O3 top-gate layers coated on Si NW channels. Drain current versus drain voltage ( I DS− V DS) and drain current versus gate voltage ( I DS− V GS) were measured for the Si NP/Si NW-based FETs to investigate their electrical and memory characteristics. The Si NW channels were depleted at V GS = 9 V, indicating that the devices functioned as p-type depletion-mode FETs. The top-gate Si NW-based FETs decorated with Si NPs show counterclockwise hysteresis loops in the I DS− V GS curves, revealing their significant charge storage effect. [ABSTRACT FROM AUTHOR]

We demonstrate a pn heterojunction diode constructed with a n-type ZnO nanowire (NW) and a p-type HgTe nanoparticle (NP) thin film on a SiO2/p-Si substrate. For the pn heterojunction diode, the rectifying characteristics of both the dark current and the photocurrent excited by 633 nm wavelength light were observed, but the photocurrent excited by 325 nm wavelength light possesses Ohmic characteristics. The optoelectronic characteristics of the pn heterojunction diode were compared with those of the ZnO NW and HgTe NP thin film composing it. [ABSTRACT FROM AUTHOR]

Photoluminescence, absorption, and photocurrent measurements were made for a hybrid system of 1-thioglycerol-capped HgTe nanoparticles synthesized by colloidal method to investigate the photocurrent mechanism in this hybrid system. Absorption and photoluminescence spectra taken for the capped HgTe nanoparticles reveal strong exciton peaks in the near-infrared wavelength range. The wavelength dependence of the photocurrent for these capped nanoparticles is very close to that of the absorption spectrum. For the photocurrent mechanism of the hybrid system, on the basis of our experimental results and energy diagram for the 1-thioglycerol-capped HgTe nanoparticles, it is suggested in this letter that holes among electron-hole pairs created by incident photons in the HgTe nanoparticles are transferred to capping 1-thioglycerol while electrons are strongly confined in these nanoparticles and that the holes contribute to the photocurrent flowing in the medium of 1-thioglycerol. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]

We construct a flexible pn heterostructured photodiode using a CdTe nanoparticle thin film and a single ZnO nanowire (NW) on a plastic substrate. The photocurrent characteristics of the flexible photodiode are examined under illumination with 325 nm wavelength light and the photocurrent efficiencies at bias voltages of +- 2.5 V are estimated to be 8.0 and 2.1 uA W [?] 1 under forward and reverse bias conditions, respectively. The photocurrent generation of the pn heterostructured photodiode is dominantly associated with the transport of the photogenerated charge carriers in the single ZnO NW. Furthermore, the operations of our flexible photodiode are investigated in the upwardly and downwardly bent states, as well as in the flat state. [ABSTRACT FROM AUTHOR]

We construct fully transparent nano-floating gate memory devices on a glass substrate. These memory thin-film transistors consist of channel layers of ZnO films, electrodes of Al/ITO, and floating gate nodes of Al nanoparticles, exhibiting a transmittance of [?] 71% in the visible region. Their electron mobility, on/off ratio, and threshold voltage shift are estimated to be 0.92 cm2 V [?] 1 s [?] 1, about 104, and 3.1 V, respectively. Moreover, their programming/erasing, endurance and retention are characterized in this study. Our study suggests that our memory devices have great potential for realizing transparent systems-on-glass. [ABSTRACT FROM AUTHOR]

Flexible electronic devices which are lightweight, thin and bendable have attracted increasing attention in recent years. In particular, solution processes have been spotlighted in the field of flexible electronics, since they provide the opportunity to fabricate flexible electronics using low-temperature processes at low-cost with high throughput. However, there are few reports which describe the characteristics of electronic devices on flexible substrates. In this study, we fabricated flexible thin-film transistors (TFTs) on plastic substrates with channel layers formed by the spin-coating of ZnO nanoparticles and investigated their electrical properties in the flat and bent states. To the best of our knowledge, this study is the first attempt to fabricate fully functional ZnO TFTs on flexible substrates through the solution process. The ZnO TFTs showed n-channel device characteristics and operated in enhancement mode. In the flat state, a representative ZnO TFT presented a very low field-effect mobility of 1.2 x 10[?]5 cm2 V[?]1 s[?]1, while its on/off ratio was as high as 1.5 x 103. When the TFT was in the bent state, some of the device parameters changed. The changes of the device parameters and the possible reasons for these changes will be described. The recovery characteristics of the TFTs after being subjected to cyclic bending will be discussed as well. [ABSTRACT FROM AUTHOR]

The transfer of charge carriers, photogenerated in nanoparticles (NPs), into a single nanowire (NW) is demonstrated in this study by conducting a careful comparison of the optoelectronic characteristics of a ZnO NW with ZnO NPs attached to its surface, a bare ZnO NW and a film of close-packed ZnO NPs. Under the illumination of an above-gap light, the photocurrent taken from the NW with the NPs is remarkably higher in magnitude than that obtained from the bare NW, although the photocurrent is substantially lower for the close-packed NPs. The presence of the absorption band of the NPs in the photoresponse spectrum taken from the NW with the NPs reveals that the transfer of the charge carriers photogenerated in the NPs into the NW dramatically enhances the magnitude of the photocurrent flowing in this NW. Nevertheless, during the transfer, the charge carriers experience trapping and detrapping at the interfaces of the NPs and the NW. [ABSTRACT FROM AUTHOR]

The photocurrent characteristics of HgTe nanoparticle (NP) thin films fabricated on glass substrates were investigated under the illumination of 1.3 µm wavelength light in this work. The photocurrent obtained from an NP thin film with a vertical structure was 119 µA in magnitude at an applied voltage of 2 V. The magnitude of the photocurrent for an NP thin film with a lateral structure was 23.8 nA at 10 V. Nevertheless, the relative magnitude of the photocurrent measured as a function of the chopping frequency was largely the same for the thin films with both the lateral and the vertical structures. The frequency-dependent photocurrent mechanism of the NP thin films will be discussed in detail in this paper. [ABSTRACT FROM AUTHOR]

Abstract: In this study, we demonstrate the photogating effects of p-type HgTe nanoparticles (NPs) on an n-type ZnO nanowire (NW). The photogating effects are due to the charge separation of the charge carriers photogenerated in the NPs under illumination and the subsequent accumulation of the photogenerated electrons in the pn junction of the NPs and the NW. The presence of the electrons in the junction reduces the current in the ZnO NW. The photogating effects are proved by the different photocurrent behavior of the ZnO NW to which the HgTe NPs are attached from that of a bare ZnO NW. In addition, the dependence of the photogating effects on the power of the incident light is discussed. [Copyright &y& Elsevier]